Stick insects hide in plain sight

November 2, 2012

A few days ago, I found a walkingstick (also called stick insects) on my screen door. These insects are very common in our area but are seldom seen because they are so perfectly camouflaged. They are long and extremely narrow and look just like twigs, especially since they often sit with their antennae and front legs held together in front in a straight line with their bodies.

Walkingsticks used to be grouped together with grasshoppers and mantises but have now been put into their own insect order, Phasmida, along with the closely related leaf insects. That name comes from the Greek word phasma, meaning a phantom, because they are nearly invisible in trees and bushes. They are very slow-moving, sitting perfectly still for long periods of time, and they feed at night.

Walkingsticks are found worldwide, but the largest ones are found in the tropics. The longest insect in the world is a walkingstick (Phobaeticus chani) from the rainforests of the island of Borneo. It is approximately 22 inches long, if its extended legs are included. The body itself is approximately 14 inches long. Giant stick insects from India and Australia are often sold as pets and do quite well in terrariums.

Article Photos

The most common walkingstick in our area, Diapheromera femorata, is about three or four inches long. The giant walkingstick of Texas (Megaphasma dentricus) is the longest insect in the United States at about seven inches. While some tropical species have wings, all of our walkingsticks are wingless except for a species in Florida that has short wings.

Walkingsticks feed on leaves of trees and shrubs. The young, called nymphs, are pale green and look just like small adults. They hatch in May or June and feed on low shrubs. As they get older, they move to trees. Some remain various shades of green, while others turn brown, gray or mottled in the colors of twigs.

Walkingsticks eat the leaves of many hardwood trees, especially black oak, black locust and wild cherry, all very common forest trees in our area, but they do not like maples. They seldom do serious damage around here, but since walkingsticks do not fly, large populations can sometimes build up and defoliate trees in a local area.

Adults mate and lay eggs in fall and die with cold weather. The females just drop their eggs randomly as they walk around in trees. I've heard it said that when there are many walkingsticks in the woods, their falling eggs sound like rain. The very hard, shiny eggs overwinter in leaf litter. In the south, the eggs hatch in spring, but in our area most do not hatch until the second year.

While their camouflage spares walkingsticks from most predators, they also have other ways of defending themselves. They produce some defensive chemicals with bad odors and some that can burn or sting a predator's eyes and mouth. And if they are grabbed by a leg, they can break that leg off and get away. They are among the few insects that can regenerate a lost leg.

Autumn is the best time to find walkingsticks because leaves are dead and falling. With nothing more to eat and their life cycles coming to an end, the insects often wander off trees and onto fences and the sides of buildings where they can be seen.

- Send your insect questions to Claire Stuart by email at buglady@wv.net or write her (with self-addressed stamped envelope) in care of Living Section, The Journal, 207 W. King St., Martinsburg, WV 25401.